nature of Science
Which step in the scientific method refers to the answer to a problem based on research an observation?
Hypothesis
. In which state of matter do the particles spread apart and fill all the space available to them?
Gas
Which of the following is an example of a physical change?
A. a candle burning C. a chicken roasting
B. an apple rotting D. sugar dissolving in water
Regan has an empty glass cup. It has a mass of 10 kg. She drops the cup on the ground, and it shatters into several pieces. If she collected all of the pieces of the cup, how much mass would all the pieces have combined?
A. There is no way to determine the mass of the shattered glass
B. Less than 10kg
C. Exactly 10 kg
D. More than 10 kg
C. exactly 10kg
what are the three subatomic particles that make up an atom?
Protons, neutrons and electrons
Bob and Lizzy are working in the lab. They are goofing off and break a glass test tube. Which rule did the break?
no playing in the lab
Which state of matter has a definite volume but not a definite shape?
Liquid
Anthony’s homework assignment is to demonstrate that an orange has already undergone a chemical change. Which of the following should he bring to class to best demonstrate a chemical change?
D. Mashed orange
B. Rotten orange
A. The ice now exists as a 100 g mass of water vapor.
B. The ice has evaporated, so the 100 g mass is destroyed.
C. The 100 g mass of ice combines with the mass of the metal sheet.
D. The ice has evaporated, producing water vapor with a mass of 10 g.
A. the ice now exists as 100g mass of water vapor
An atom’s mass number is 31 and its atomic number is 15. How many neutrons does the atom have?
a. 15
b. 16
c. 31
d. 46
B. 16
Connie and Amelia are timing how fast marbles roll down an inclined plane. They plan to do this 5 times, and then take the average time for their results. What would be the BEST way to improve the accuracy of their data?
repeating the experiment multiple times
Scott and Jasmine are trying to classify several objects that they found during a field trip to the beach. They collected a sample of seawater, a piece of driftwood, and several smooth pebbles. What property does the driftwood share with the pebbles that it does not share with the water?
A. Its particles move freely in all directions.
B. Its particles vibrate, but are locked in place.
C. Its shape depends on its container.
D. Its volume will change in different containers.
B. Its particles vibrate, but are lock in place
When a substance goes through a chemical change, it forms a new substance that has different physical and chemical properties. Often, chemical changes are caused by changes in temperature. Which of the following is a chemical change caused by a change in temperature?
A. ice cream melting
B. water boiling
C. cake baking
D. chicken freezing
C. cake baking
All of the devices below either use or produce electrical energy. Which one converts mechanical energy to electrical energy?
A. Wind Turbine B.Battery
C. Electrical drill
D Electric guitar
A. wind turbine
Even though atoms are much too small to see, experiments have helped scientists learn about the subatomic particles that compose atoms. The current model of an atom has a nucleus in the center surrounded by an electron cloud. Which of these parts of the atom has the greatest mass and why
The nucleus, because it contains protons and neutron, electrons mass is almost zero
Two scientists are conducting similar experiments. The results of their experiments are very different. Which of the following would be best for the scientists to do next?
A.Assume that both scientists are correct.
B.Change the experiment that is incorrect.
C.Redo the experiments to see who is correct.
D. Determine that both scientists are incorrect
C. redo the experiements to see who is correct
What is the state of matter in which the attractive forces between particles are the greatest?
Solid
An experiment was performed in which a crystalline substance was added to a beaker filled with a liquid at room temperature. The observations made during the experiment were as follows:
1. The crystals subliming
2. A precipitate formed.
3. The bottom of the beaker felt warm to the touch.
4. Bubbles formed in the water.
All of the observations are evidence that a chemical change occurred EXCEPT–
1. The crystal subliming
It takes 100 Joules of energy lift a box off the floor to put it onto a shelf. If the box fell off the shelf how much energy would it have before it hits the floor?
A. 100 Joules of potential energy B. 100 Joules of kinetic energy
C. Greater than 100 Joules of potential energy
D. Greater than 100 Joules of kinetic energy
B. 100 joules of kinetic energy
If you know the number of neutrons and the mass of an atom how can you determine the identity of the atom?
find the number of protons, atomic number tell the identity of atoms
David and Jeremiah are going to conduct an experiment to see whether salt affects the growth of plants. They assemble five groups of identical plants and give the plants in each group water with a different salt concentration. What is the outcome variable (dependent variable) for their experiment?
A. Salt concentration in plant tissue
B. Salt concentration in plant water
C. Amount of water absorbed by plants
D. Average mass of plants in each group
D. average mass of plants in each group
Ben wants to model how the motion of particles changes with temperature. He considers water in an iron pot. Ben draws a model to show how the water particles and iron particles move at room temperature. Then, he draws a second model to show how the water particles and iron particles move as the pot of water is heated. How should Ben’s second model differ from the first?
A. The water particles should vibrate faster, and the iron particles should not move.
B. Both the water particles and the iron particles should slide past each other faster.
C. The water particles should slide past each other faster, and the iron particles should vibrate faster.
D. The water particles should move freely in all directions, and the iron particles should slide past each other faster.
C. The water particles should slide past each other faster and the iron particles should vibrate faster
Layton added a silvery white metal to a beaker of cold water and noticed that gas bubbles were given off and a different substance formed. When he repeated the activity with hot water he noticed the gas bubbles were released much more rapidly. why did the reaction occurred faster in hot water?
particles gain kinetic energy and collide faster in hot water
Tamara adds 20g of baking soda to 100g of sulfuric acid. The mixture begins to bubble. When the bubbling stops, Tamara finds the mass of the resulting mixture. She determines its mass is 115 g. Why has the mass changed?
A. A gas has formed and left the mixture.
B. Sulfuric acid evaporated during the experiment.
C. Mixtures always are less massive than their parts.
D. Mass was destroyed when sulfuric acid reacted with baking soda.
A. a gas has form and left the mixture
Krypton (Kr) has an atomic number of 36. With only this information, is possible to determine the number of electrons and if so how many
yes the number of protons equal number of electron